The role of hexokinase isoenzymes on control of adipose tissue metabolism will be studied. Rat adipose tissue will be incubated for 18 hours in the presence of agents which are known to alter hexokinase (glucose, insulin, 2-deoxyglucose, dexamethasone), then isolated fat cells will be made and hexokinase isoenzymes in the fat cells will be compared with rates of glucose utilization in the presence and absence of insulin during a subsequent 2-hour incubation. Transport of glucose into the cell will be measured in other studies after appropriate incubation periods. In order to determine the importance of changes in enzyme activity, isolated fat cells will be made from normal rats, olds rats, dexamethasone-treated rats, and tissue incubated as above. The cells will be incubated briefly under varying conditions and metabolites related to phosphorylation and pentose shunt will be measured. These include glucose, glucose-6-phosphate, ATP, ADP, NADP, NADPH, and 6- phosphogluconate. From this it will be determined which step is rate limiting in states of insulin insensitivity. Specific antibodies to hexokinase-11 will be made. Fat cells will be incubated with 3H amino acids under appropriate conditions, and incorporation of label into the enzyme will be determined by immunoprecipitation. Degradation of enzyme will be studied on prelabeled cells.